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Building the Digital Collection

The University of Chicago Library received an award in the 1996/97
round of the Library of Congress / Ameritech National Digital Library
Competition to support the digitization of this collection of photographs
of the environment. As encouraged by the guidelines, the image files are
mounted and maintained at the University of Chicago. Descriptive
bibliographic records were delivered to the Library of Congress for
indexing as part of American Memory. Each record includes links to the
corresponding image files.

Digitizing the Collection

Original media (glass lantern slides, glass negatives and photographic
prints) were scanned by project staff
at the University of Chicago Library
using an Agfa Duoscan 8.5" x 14" flatbed scanner with a transparency
adapter. Original scans were captured at 600 dpi, 8-bit grayscale.
Quality control was accomplished by inspecting the images on screen for
skew and image quality. The high resolution uncompressed TIFF files are
written to CD media for long term storage. Using Debabelizer software,
two access images were derived from each file: a high resolution JPEG
compressed image measuring approximately 875 x 650 pixels for reference,
and a GIF image for display with the bibliographic record on the American
Memory site. More than 90 percent of these derived images were created in
batch mode using Debabelizer scripts. Because of the variation in size
among the photographic prints they were processed in smaller batches and a
few prints were scaled individually.

Cataloging the Collection

The database of bibliographic records that support access to the images was
constructed using Microsoft Access to create a table with forty-six data fields.
The fields included caption, photographer, slidemaker, date of original photograph, subject
terms and a unique identifier. Descriptive information input into the
database was taken from the slide labels, fronts and backs of photographic
prints, glass negative sleeves, notebooks and photographic print
albums.

Subject authorities used were Library of Congress Subject
Headings, the Thesaurus for Graphic Materials of the Library of
Congress Prints and Photographs Division (LCTGM) and the Art and
Architecture Thesaurus (AAT (external link)) of the
Getty Research Institute. Supplementary authorities include A Glossary
of Geographical Terms, edited by Dudley Stamp and Audrey Clark,
London: Longman, 1979 and Encyclopedic Dictionary of Physical
Geography by Andrew Goudie, et al, Oxford: Basil Blackwell, 1985.

Interoperability between the Library of Congress and the University
of Chicago

The descriptive metadata for the American Environmental Photographs was
extracted directly from the Access database of bibliographic records using
SQL and ODBC and converted into SGML using a Python program according to a
locally written Document Type Definition (DTD) for the data. The
converted data was run through an SGML validator before being shipped to
the Library of Congress. The records were transformed automatically at
the Library of Congress to facilitate indexing by the InQuery search
engine and to allow records for this collection to be distinguished from
other American Memory collections.

Individual image descriptions are displayed through American Memory with a
thumbnail of the image; clicking on the thumbnail invokes delivery of
the higher resolution image. The image files are maintained on University
of Chicago Library servers. The images are accessed from the bibliographic
description via a unique identifier which forms part of the address
for the image. The unique identifier has been constructed for each image
by using a combination of letters and numbers to represent the project
name, state, medium and accession number. The name of the electronic
collection is American Environmental Photographs, abbreviated AEP. Two-letter
postal abbreviations identify each state. The letters S, N and P indicate
slides, negatives and photographs respectively and the accession numbers
begin with 1 and continue as needed for each subset of images. An example
of an image identifier is AEP-ALS10, which stands for the American Environmental
Photographs Collection, Alaska, slide format, image number 10.